Influence of observer-dependency on left ventricular hypertrabeculation mass measurement and its relationship with left ventricular volume and ejection fraction –  comparison between manual and semiautomatic CMR image analysis methods

BACKGROUND: Recent studies concerning left ventricular noncompaction (LVNC) suggest that the extent of left ventricular (LV) hypertrabeculation has no impact on prognosis. The variety of methods of LV noncompacted myocardial mass (NCM) assessment may influence the results. Hence, we compared two methods of NCM estimation: largely observer-independent Hautvast’s((H)) computed algorithm-based approach and commonly used Jacquier’s((J)) method, and their associations with LV end-diastolic volume (EDV) and ejection fraction (EF). METHODS: Cardiac magnetic resonance images of 77 persons (45±17yo) - 42 LVNC, 15 non-ischemic dilative cardiomyopathy, 20 control group were analyzed. LVNC patients were divided into the subgroup with normal (LVNC(N)) and high EDV (LVNC(DCM)). NCM and total left ventricular mass (LVM) were estimated by Hautvast’s [excluding intertrabecular blood (ITB) and including papillary muscles (PMs) into NCM] and Jacquier’s approach (including ITB and PMs, if unclearly distinguished, into NCM). RESULTS: The cut-off value of NCM for LVNC diagnosis was 22% (AUC 0.933) for NCM(H)/LVM(H) and 26% (AUC 0.883) for NCM(J)/LVM(J). Inter- and intra-observer variability (estimated by coefficient of variation [CoV] and intraclass correlation coefficient [ICC]) of NCM(H)/LVM(H) appeared better than of NCM(J)/LVM(J) (CoV 4.3%, ICC 0.981 and CoV 4.9%, ICC 0.978; respectively for NCM(H)/LVM(H), while for NCM(J)/LVM(J): CoV 19.7%, ICC 0.15 and CoV 12.9%, ICC 0.504). In LVNC(N) subgroup, the correlation between EDV and NCM(H) was stronger than NCM(J) (r = 0.677, p<0.001 vs. r = 0.480, p = 0.038; respectively). In LVNC the EDV correlated with NCM(H)/LVM(H) (r = 0.391, p<0.01), but not with NCM(J)/LVM(J). In the overall group a relationship was present between EF and NCM(H)/LVM(H) (r = -0.449, p<0.001), but not NCM(J)/LVM(J). Only NCM(H)/LVM(H) explained the variability of EDV (b 0.434, p<0.001). CONCLUSIONS: Choosing a method of NCM assessment that is less observer-dependent might increase the reliability of results. The impact of method selection on the LV parameters and cut-off values for hypertrabeculation should be further investigated.